Organic electroluminescent materials and devices

ABSTRACT

Triphenylene containing benzo-fused thiophene compounds are provided. Additionally, triphenylene containing benzo-fused furan compounds are provided. The compounds may be useful in organic light emitting devices, particularly as hosts in the emissive layer of such devices, or as materials for enhancement layers in such devices, or both.

This application is a continuation of U.S. application Ser. No.14/335,076, filed Jul. 18, 2014, which is a continuation of U.S.application Ser. No. 13/714,872, filed Dec. 14, 2012, now U.S. Pat. No.8,822,708, which is a divisional application of U.S. application Ser.No. 12/672,198, filed May 26, 2010, now U.S. Pat. No. 8,367,850, whichis a §371 National Stage Entry of International Application Serial No.PCT/US2008/072499, filed Aug. 7, 2008, which claims priority to U.S.Provisional Application Ser. No. 60/963,944, filed Aug. 8, 2007, U.S.Provisional Application Ser. No. 61/017,506, filed Dec. 28, 2007, andU.S. Provisional Application Ser. No. 61/017,391, filed Dec. 28, 2007,the disclosures of which are expressly incorporated herein by referencein their entirety.

JOINT RESEARCH AGREEMENT

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: The Regents of the University ofMichigan, Princeton University, University of Southern California, andUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to novel organic materials having abenzo-fused thiophene and/or a benzo-fused furan and a triphenylene. Inparticular, the materials have a dibenzothiophene and/or benzofuran anda triphenylene. The materials may be useful in light emitting devices(OLEDs).

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand is referred to as “photoactive” when it is believed that theligand contributes to the photoactive properties of an emissivematerial.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

Triphenylene containing benzo-fused thiophene compounds are provided.The compounds may be useful in organic light emitting devices. Thecompounds may be particularly useful as the host of an emissive layer ofan organic light emitting device, as a material for an enhancementlayer, or both.

Examples of triphenylene-containing benzo-fused thiophenes includecompounds having the structure of Formula (I), Formula (II), and Formula(III):

R₁, R₂ and R₃ are independently selected from alkyl, alkoxy, amino,alkenyl, alkynyl, arylkyl, aryl, heteroaryl and hydrogen. Each of R₁, R₂and R₃ may represent multiple substituents. At least one of R₁, R₂ andR₃ includes a triphenylene group. The triphenylene group may be linkeddirectly to the structure of Formula (I), (II) or (III), but there mayalso be a “spacer” in between the triphenylene group and the structureof Formula (I), (II) or (III).

Examples of triphenylene containing benzo-fused thiophenes orbenzo-fused furans include compounds having the structure:

X is S or O. Preferably, R₁, R₂, and R₃ are unfused substituents thatare independently selected from C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁,N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CC_(n)H_(2n+1),Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution. Each of R₁, R₂, andR₃ may represent mono, di, tri, or tetra substitutions. n is 1, 2, 3, 4,5, 6, 7, 8, 9, or 10. Ar₁ and Ar₂ are independently selected from thegroup consisting of benzene, biphenyl, naphthalene, triphenylene,carbazole, and heteroaromatic analogs thereof. At least one of R₁, R₂,and R₃ includes a triphenylene group.

More specific examples of useful triphenylene containing benzo-fusedthiophene compounds and triphenylenes containing benzo-fused furancompounds include Compounds 1G-48G and Compounds 1-48, as disclosedherein. The compounds may be useful as the host of an emissive layer ofan organic light emitting device, a enhancement layer material of such adevice, or both.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows triphenylene-containing benzo-fused thiophene and/orbenzo-fused furan compounds.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, and a cathode 160. Cathode 160 is acompound cathode having a first conductive layer 162 and a secondconductive layer 164. Device 100 may be fabricated by depositing thelayers described, in order. The properties and functions of thesevarious layers, as well as example materials, are described in moredetail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporatedby reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety. An “enhancement layer” occupies the sameposition in a device as a blocking layer described above, and may haveblocking functionality or other functionality that improves deviceperformance.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. patent application Ser. No. 10/233,470, which is incorporated byreference in its entirety. Other suitable deposition methods includespin coating and other solution based processes. Solution basedprocesses are preferably carried out in nitrogen or an inert atmosphere.For the other layers, preferred methods include thermal evaporation.Preferred patterning methods include deposition through a mask, coldwelding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819,which are incorporated by reference in their entireties, and patterningassociated with some of the deposition methods such as ink-jet and OVJD.Other methods may also be used. The materials to be deposited may bemodified to make them compatible with a particular deposition method.For example, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, televisions, billboards, lights forinterior or exterior illumination and/or signaling, heads up displays,fully transparent displays, flexible displays, laser printers,telephones, cell phones, personal digital assistants (PDAs), laptopcomputers, digital cameras, camcorders, viewfinders, micro-displays,vehicles, a large area wall, theater or stadium screen, or a sign.Various control mechanisms may be used to control devices fabricated inaccordance with the present invention, including passive matrix andactive matrix. Many of the devices are intended for use in a temperaturerange comfortable to humans, such as 18 degrees C. to 30 degrees C., andmore preferably at room temperature (20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, and heteroaryl are known to the art, and aredefined in U.S. Pat. No. 7,279,704 at cols. 31-32, which areincorporated herein by reference.

Compounds are provided, comprising a triphenylene-containing benzo-fusedthiophene. Triphenylene is a polyaromatic hydrocarbon with high tripletenergy, yet high π-conjugation and a relatively small energy differencebetween the first singlet and first triplet levels. This would indicatethat triphenylene has relatively easily accessible HOMO and LUMO levelscompared to other aromatic compounds with similar triplet energy (e.g.,biphenyl). The advantage of using triphenylene and its derivatives ashosts is that it can accommodate red, green and even blue phosphorescentdopants to give high efficiency without energy quenching. Triphenylenehosts may be used to provide high efficiency and stability PHOLEDs. SeeKwong and Alleyene, Triphenylene Hosts in Phosphorescent Light EmittingDiodes, 2006, 60 pp, US 2006/0280965 A1. Benzo-fused thiophenes may beused as hole transporting organic conductors. In addition, the tripletenergies of benzothiophenes, namely dibenzo[b,d]thiophene (referred toherein as “dibenzothiophene”), benzo[b]thiophene and benzo[c]thiopheneare relatively high. A combination of benzo-fused thiophenes andtriphenylene as hosts in PHOLED may be beneficial. More specifically,benzo-fused thiophenes are typically more hole transporting thanelectron transporting, and triphenylene is more electron transportingthan hole transporting. Therefore combining these two moieties in onemolecule may offer improved charge balance which may improve deviceperformance in terms of lifetime, efficiency and low voltage. Differentchemical linkage of the two moieties can be used to tune the propertiesof the resulting compound to make it the most appropriate for aparticular phosphorescent emitter, device architecture, and/orfabrication process. For example, m-phenylene linkage is expected toresult in higher triplet energy and higher solubility whereasp-phenylene linkage is expected to result in lower triplet energy andlower solubility.

Similar to the characterization of benzo-fused thiophenes, benzo-fusedfurans are also typically hole transporting materials having relativelyhigh triplet energy. Examples of benzo-fused furans include benzofuranand dibenzofuran. Therefore, a material containing both triphenylene andbenzofuran may be advantageously used as host or hole blocking materialin PHOLED. A compound containing both of these two groups may offerimproved electron stabilization which may improve device stability andefficiency with low voltage. The properties of the triphenylenecontaining benzofuran compounds may be tuned as necessary by usingdifferent chemical linkages to link the triphenylene and the benzofuran.

The compounds may be substituted with groups that are not necessarilytriphenylenes, benzo-fused thiophenes, and benzo-fused furans.Preferably, any group that is used as a substituent of the compound hasa triplet energy high enough to maintain the benefit of havingtriphenylene benzo-fused thiophenes or benzo-fused furans (i.e. thetriplet energy of the substituent maintains the high triplet energy ofbenzo-fused thiophenes, benzo-fused furans and triphenylenes). Examplesof such groups that may be used as substituents of the compound mayinclude any substituent selected from C_(n)H_(2n+1), OC_(n)H_(2n+1),OAr₁, N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1),C≡CC_(n)H_(2n+1), Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution,wherein n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and wherein Ar₁ and Ar₂are independently selected from the group consisting of benzene,biphenyl, naphthalene, triphenylene, carbazole, and heteroaromaticanalogs thereof. The compounds described herein have a high enoughtriplet energy to be suitable for use in a device having phosphorescentblue emissive materials.

The substituents of the compounds described herein are unfused such thatthe substituents are not fused to the triphenylene, benzo-fused furan orbenzo-fused thiophene moieties of the compound. The substituents mayoptionally be inter-fused (i.e. fused to each other).

In addition to improved device stability and efficiency, the materialsprovided herein may also offer improved film formation in the device asfabricated by both vapor deposition and solution processing methods. Inparticular, materials offering improved fabrication have a centralpyridine ring to which the benzo-fused thiophenylene and triphenylene,or benzofuran and triphenylene, are attached. The improved filmformation is believed to be a result of the combination of polar andnon-polar rings in the compound.

Examples of triphenylene-containing benzo-fused thiophenes includecompounds having the structure of Formula (I), Formula (II), and Formula(III):

R₁, R₂ and R₃ are independently selected from alkyl, alkoxy, amino,alkenyl, alkynyl, arylkyl, aryl, heteroaryl and hydrogen. Each of R₁, R₂and R₃ may represent multiple substituents. At least one of R₁, R₂ andR₃ includes a triphenylene group. The triphenylene group may be linkeddirectly to the structure of Formula (I), (II) or (III), but there mayalso be a “spacer” in between the triphenylene group and the structureof Formula (I), (II) or (III).

Examples of triphenylene containing benzo-fused thiophenes orbenzo-fused furans include compounds having the structure:

X is S or O. Preferably, R₁, R₂, and R₃ are unfused substituents thatare independently selected from C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁,N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CC_(n)H_(2n+1),Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution. Each of R₁, R₂, andR₃ may represent mono, di, tri, or tetra substitutions. n is 1, 2, 3, 4,5, 6, 7, 8, 9, or 10. Ar₁ and Ar₂ are independently selected from thegroup consisting of benzene, biphenyl, naphthalene, triphenylene,carbazole, and heteroaromatic analogs thereof. At least one of R₁, R₂,and R₃ includes a triphenylene group.

Examples of compounds having the structure of Formula (I) include:

R₁ to R_(n) represents, independently, mono, di, tri or tetrasubstitutions selected from alkyl, alkoxy, amino, alkenyl, alkynyl,arylkyl, aryl and heteroaryl, or no substitution.

Examples of compounds having the structure of Formula (IV) include:

X is S or O. Preferably, X is S. R₁ to R_(n) are independently selectedfrom the group consisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁,N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CC_(n)H_(2n+1),Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution. Each of R₁ to R_(n)may represent mono, di, tri, or tetra substitutions. n is 1, 2, 3, 4, 5,6, 7, 8, 9, or 10. Ar₁ and Ar₂ are independently selected from the groupconsisting of benzene, biphenyl, naphthalene, triphenylene, carbazole,and heteroaromatic analogs thereof. At least one of R₁, R₂, and R₃includes a triphenylene group.

Examples of compounds having the structure of Formula (II) include:

R₁ to R_(n) represents, independently, mono, di, tri or tetrasubstitutions selected from alkyl, alkoxy, amino, alkenyl, alkynyl,arylkyl, aryl and heteroaryl, or no substitution.

Examples of compounds having the structure of Formula (V) include:

X is S or O. Preferably, X is S. R₁ to R_(n) are independently selectedfrom the group consisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁,N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CC_(n)H_(2n+1),Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution. Each of R₁ to R_(n)may represent mono, di, tri, or tetra substitutions. n is 1, 2, 3, 4, 5,6, 7, 8, 9, or 10. Ar₁ and Ar₂ are independently selected from the groupconsisting of benzene, biphenyl, naphthalene, triphenylene, carbazole,and heteroaromatic analogs thereof. At least one of R₁, R₂, and R₃includes a triphenylene group.

Examples of compounds having the structure of Formula (III) include:

R₁ to R_(n) represents, independently, mono, di, tri or tetrasubstitutions selected from alkyl, alkoxy, amino, alkenyl, alkynyl,arylkyl, aryl and heteroaryl, or no substitution.

Examples of compounds having the structure of Formula (VI) include:

X is S or O. Preferably, X is S. R₁ to R_(n) are independently selectedfrom the group consisting of C_(n)H_(2n+1), OC_(n)H_(2n+1), OAr₁,N(C_(n)H_(2n+1))₂, N(Ar₁)(Ar₂), CH═CH—C_(n)H_(2n+1), C≡CC_(n)H_(2n+1),Ar₁, Ar₁—Ar₂, C_(n)H_(2n)—Ar₁, or no substitution. Each of R₁ to R_(n)may represent mono, di, tri, or tetra substitutions. n is 1, 2, 3, 4, 5,6, 7, 8, 9, or 10. Ar₁ and Ar₂ are independently selected from the groupconsisting of benzene, biphenyl, naphthalene, triphenylene, carbazole,and heteroaromatic analogs thereof. At least one of R₁, R₂, and R₃includes a triphenylene group.

Each of the triphenylene-containing benzo-fused thiophenes disclosedabove may be advantageously used in an organic light emitting device.The compounds are particularly useful for use as the host of an emissivelayer in an organic light emissive device, an enhancement layer materialof such a device, or both.

EXPERIMENTAL Compound Examples Example 14-(triphenylen-2-yl)dibenzothiophene (Compound 1S) 1. Synthesis of2-Bromotriphenylene

The synthesis of the compound above was described in US20060280965.

2. Synthesis of 4-(triphenylen-2-yl)dibenzothiophene

4.4 g (14.6 mmol) of 2-bromotriphenylene, 4.0 g (17.5 mmol) of4-dibenzothiopheneboronic acid, 0.51 g (0.44 mmol) oftetrakistriphenylphosphinepalladium, and 4.0 g (43.4 mmol) of potassiumcarbonate were charged in a 250 mL round bottom flask with solvent 90 mLof toluene and 10 mL of water. The reaction mixture was purged withnitrogen for 30 min and then was heated up to reflux for overnight undernitrogen with stirring. The reaction mixture was cooled and the organicextracts were purified by column chromatography and recrystallizationwith toluene. 5.1 g (86%) of white solid was obtained as the productwhich was confirmed by proton NMR.

Example 2 4-(3-(triphenylen-2-yl)phenyl)dibenzothiophene (Compound2S) 1. Synthesis of 3-(2-triphenylene)phenyl trifluoromethanesulfonate

The synthesis of the above compound was described ProvisionalApplication No: 60/963,944.

2. Synthesis of 4-(3-(triphenylen-2-yl)phenyl)dibenzothiophene

4.52 g (10.0 mmol) of 3-(triphenylen-2-yl)phenyltrifluoromethanesulfonate, 3.0 g (13.0 mmol) of4-dibenzothiopheneboronic acid, 0.46 g (0.5 mmol) of Pd₂(dba)₃, 0.82 g(2.0 mmol) of 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl, 12.7 g(60.0 mmol) of K₃PO₄ and 150 mL of toluene and 15 mL of water werecharged in a 250 mL round bottom flask. The reaction mixture was heatedup to reflux under nitrogen for overnight. The reaction mixture wascooled and the organic extracts were purified by column chromatographyand recrystallization. 4.3 g (88%) of white solid was obtained asproduct which was confirmed by proton NMR.

Example 3 2,8-di(triphenylen-2-yl)dibenzothiophene (Compound 5S) 1.Synthesis of4,4,5,5-tetramethyl-2-(triphenylen-2-yl)-1,3,2-dioxaborolane

The synthesis of this compound was described in US2006/0280965.

1. Synthesis of 2,8-di(triphenylen-2-yl)dibenzothiophene

2.25 g (6.3 mmol) of4,4,5,5-tetramethyl-2-(triphenylen-2-yl)-1,3,2-dioxaborolane, 0.92 g(2.7 mmol) of 2,8-dibromodibenzothiophene, 0.12 g (0.14 mmol) ofPd₂(dba)₃, 0.22 g (0.53 mmol) of2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl, 3.4 g (16.0 mmol) ofK₃PO₄, 100 mL of toluene and 10 mL of water were charged in a 250 mLround bottom flask. The reaction mixture was purged with nitrogen for 20min and then heated up to reflux for overnight with stirring. Thereaction mixture was cooled and filtered. The white solid was washedwith methanol 3 times (3×100 mL) and methylene chloride (2×100 mL). 1.6g of (94% yield) solid was obtained as the product which was furtherpurified by recrystallization with toluene and sublimation. The productwas confirmed by solid probe MS.

Example 4 Compound 20S 1. Synthesis of 2-bromodibenzothiophene

15 g (79.9 mmol) dibenzothiophene was dissolved in 1.5 L chloroform. Tothe solution, 12.76 g (79.9 mmol) bromine was added dropwise. Thereaction mixture was vigorously stirred for 2 days at room temperatureand then treated with sodium sulfite water solution. The organic phasewas evaporated to give a white solid which has 48% unreacteddibenzothiophene, 50% 2-bromodibenbzothiophene and ˜less 2%2,8-dibromodibenzothiophene based on GC-MS and HPLC results. The mixturewas repeatedly recrystallized with ethyl acetate to get pure2-bromodibenzothiophene.

2. Synthesis of Boron Ester Product

8 g (17.5 mmol) 3-(2-triphenylene)phenyl trifluoromethanesulfonate, 9.1g (35.2 mmol) bis(pinacolato)diboron, 290 mg (0.35 mmol) Pd(dffp)₂Cl₂,5.2 g (52.5 mmol) KOAc and 150 mL anhydrous dioxane were charged in a250 mL three-necked flask. The reaction mixture was heated up to 90° C.under nitrogen for 20 hours. 7.0 g white solid was obtained after columnwith 30% ethyl acetate in hexane as elute. The product was confirmed byproton NMR.

3. Synthesis of Compound 20S

2 g (7.1 mmol) 2-bromodibenzothiophene, 4.0 g (9.3 mmol) boron esterproduct in Step 2, 325 mg (0.355 mmol) Pd₂(dba)₃, 582 g (1.4 mmol)S-phose, 9 g (42 mmol) K₃PO₄, 90 mL toluene and 10 mL water were chargedin a 250 mL flask. The reaction mixture was heated up to reflux undernitrogen for overnight. The reaction mixture was extracted withmethylene chloride and the organic extracts were purified by silica gelcolumn chromatography and recrystallization. ˜2.9 g (85%) white solidwas obtained as product which was confirmed by proton NMR.

Example 5 Compound 10S 1. Synthesis of 4,4′dimethoxy-o-terphenyl

A mixture was prepared consisting of 1,2-dibromobenzene (50 g, 212mmol), 4-methoxyphenylboronic acid (78 g, 513 mmol), triphenylphosphine(11.12 g, 42.2 mmol), potassium carbonate (73.25 g, 530 mmol),dimethoxyethane (290 mL), and water (290 mL). Nitrogen was bubbleddirectly into the mixture for 20 minutes. Palladium acetate was added(4.76 g, 21.2 mmol) and the mixture was heated to reflux overnight undernitrogen. The reaction mixture was cooled and water and dichloromethanewas added. The layers were separated and the aqueous layer was extractedwith dichloromethane. The combined organic layers were filtered throughCelite and washed with brine, dried over magnesium sulfate, filtered,evaporated to a yield a black oil. The crude material was purified bycolumn chromatography eluting with 0 to 100% dichloromethane in hexane.The major fractions were purified by distillation using Kugelrohr at 200to 220° C. 49 g (80%) product was obtained.

2. Synthesis of 2,11-dimethoxytriphenylene

12.4 g (42.7 mmol) of 4,4′dimethoxy-o-terphenyl and 16 g (63.0 mmol)iodine chips was placed in a 250 mL reaction vessel. 200 mL of toluenewas added followed by 30 mL of propylene oxide. The photoreactor was setup with a condenser cooled by a circulating chiller. A 400 W mediumpressure mercury lamp was used as the light source. The reaction vesselwas placed in a cabinet. The lamp was ignited and the chillertemperature was set such that the water exiting the reactor wasmaintained at between 20° C. and 25° C. (monitored by a thermocoupleattached the exit stream). The reaction was left on for 18 hours. Asolid was filtered off and washed with hexanes, only recovered 2.2 g ofmaterial. The filtrate was diluted with toluene and washed with sodiumsulfate solution. The aqueous layer was back extracted with toluene andthe organic layers were dried over magnesium sulfate, filtered, andevaporated. Material was dissolved in toluene and added sodium sulfitesolution and stirred. The layers were separated, the aqueous layerextracted with toluene and the combined organic layers were dried overmagnesium sulfate, filtered, and evaporated. The residue was purified bycolumn chromatography eluting with 0 to 100% ethyl acetate/hexane. 8.8 gmaterial (72%) was obtained.

3. Synthesis of triphenylene-2,11-diol

A mixture of 2,11-dimethoxytriphenylene (8.8 g, 30.5 mmol) and pyridinehydrochloride (31.73 g, 274.6 mmol) was heated to 220° C. for 2 hours.The mixture was cooled and water was added. The resulting solid wasfiltered off, washed with water, and dried under high vacuum. 7.45 g(94%) desired product was obtained.

4. Synthesis of triphenylene-2,11-diyl bis(trifluoromethanesulfonate)

Triphenylene-2,11-diol (7.45 g, 28.62 mmol) was added to 100 mLdichloromethane and 13 mL pyridine and the solution was cooled in an icesalt bath. Trifluoromethanesulfonic anhydride (19 mL, 114.49 mmol) in 70mL of dichloromethane was added dropwise to the solution under nitrogen.The reaction was allowed to proceed for 2 hours and quenched by addingby adding methanol and water followed by dilution with dichloromethane.A tan solid was filtered off and washed with dichloromethane and water.The layers in the filtrate were separated and the aqueous layer wasextracted with dichloromethane. The organic extracts were dried overmagnesium sulfate, filtered, and evaporated to yield a brown solid. Thebrown solid was purified by column chromatography eluting with 0 to 100%dichloromethane/hexane following sublimation at 170° C. andrecrystallization twice from 300 mL boiling toluene. 11.4 g product wasobtained (76%).

5. Synthesis of Compound 10S

A mixture of triphenylene-2,11-diyl bis(trifluoromethanesulfonate) (1.5g, 2.9 mmol), dibenzothiophene-4-boronic acid (2.6 g, 11.4 mmol),potassium fluoride (1.1 g, 19 mmol) and THF 50 mL was prepared. Nitrogenwas bubbled directly in the mixture for 1 hour. Next potassium acetate(13 mg, 0.06 mmol) and triscyclohexyl phosphine (19 mg, 0.07 mmol) wasadded, and then nitrogen was bubbled in the mixture for another 30minutes. The mixture was heated at 50° C. overnight. Then the reactionwas cooled to room temperature. The precipitation was collected byfiltration. The white solid was put in one soxhlet extractor and washedby refluxing THF overnight. The solid in the extractor was collect toprovide 0.9 gram white solid (yield 53%).

Example 6 Compound 9S 1. Synthesis of2-(3′-methoxybiphenyl-3-yl)triphenylene

12.9 g (28.5 mmol) 3-(triphenylen-2-yl)phenyl trifluoromethanesulfonate,6.5 g (42.8 mmol) 3-methoxyphenylboronic acid, 0.47 g (1.1 mmol)2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (SPhos) and 18.2 g (85.5mmol) potassium phosphate tribasic (K₃PO₄) were weighed in a roundbottom flask. 150 mL toluene and 80 mL water were added to the flask assolvent. The solution was purged with nitrogen and 0.26 g (0.28 mmol) oftris(dibenzylideneacetone)dipalladium (0) [Pd₂(dba)₃] was added. Thesolution was heated to reflux for twelve hours. Upon cooling, theorganic layer was separated, and dried with MgSO₄. The product wasreadily separated by column chromatography using hexane/dichloromethaneas eluent (1/0 gradient to 3/2). The solvent was removed by rotaryevaporation resulting in 11.7 g (28 mmol) of the product,2-(3′-methoxybiphenyl-3-yl)triphenylene.

2. Synthesis of 3′-(triphenylen-2-yl)biphenyl-3-ol

In a round bottom flask under nitrogen, 11.5 g (28 mmol)2-(3′-methoxybiphenyl-3-yl)triphenylene and 21.1 g (183 mmol) pyridinehydrochloride were heated to 204° C. Upon cooling, water was added andextracted with dichloromethane. The combined organic fractions werewashed with additional water and the solvent was removed by rotaryevaporation. The solid was drypacked on celite and the product purifiedby column chromatography using hexanes:dichloromethane (1:4) as eluent.The solvent was removed by rotary evaporation resulting in 8.6 g (22mmol) of the product, 3′-(triphenylen-2-yl)biphenyl-3-ol.

3. Synthesis of 3′-(triphenylen-2-yl)biphenyl-3-yltrifluoromethanesulfonate

8.6 g (22 mmol) of 3′-(triphenylen-2-yl)biphenyl-3-ol was added to aflask under nitrogen with 3.4 g (43.4 mmol) anhydrous pyridine and 450mL anhydrous dichloromethane. The solution was cooled in an ice bath and12.2 g (43.4 mmol) trifluoromethanesulfonic anhydride (Tf₂O) was addedslowly via syringe. The solution was warmed to room temperature andstirred overnight. The solution was washed with water, dried with MgSO₄and solvent was removed by rotary evaporation. The product,3′-(triphenylen-2-yl)biphenyl-3-yl trifluoromethanesulfonate, waspurified by column chromatography using hexane/dichloromethane as eluent(1/0 to 1/1 gradient) resulting in 10.7 g (20.2 mmol).

4. Synthesis of Compound 9S

5.5 g (10.4 mmol) product in above Step 3, 3.0 g (13.5 mmol) 4-boronicacid dibenzothiophene, 458 mg (0.5 mmol) Pd₂(dba)₃, 820 mg (2 mm01)S-phose, 12.7 g (60 mmol) potassium phosphate and 150 mL toluene wereadded in a 250 flask. The reaction mixture was heated up to reflux undernitrogen overnight. Then it was cooled down and worked up. ˜5 g whiteproduct was obtained after silica gel column chromatography with 20%methylene chloride in hexane as elute and following with washing withmethanol. The product was confirmed by proton NMR.

Example 7 Compound 19S 1. Synthesis of 3,3′-dimethoxy-o-terphenyl

1,2-dibromobenzene (50.0 g, 0.212 mol), 3-methoxyphenylboronic acid(77.3 g, 0.509 mol), palladium acetate (1.2 g, 5.33 mmol),triphenylphosphine (21.4 mmol), sodium carbonate (78.9 g, 0.744 mol)were combined with dimethoxyethane (430 mL) and water (290 mL) in a 2000mL round-bottom flask equipped with a stir bar, reflux condenser, and anitrogen inlet and heated at reflux for 4 days. Ethyl acetate (500 mL)was added and the organic layer was separated, dried over magnesiumsulfate, and evaporated to dryness to yield 61.3 g (99.7%) of3,3′-dimethoxy-o-terphenyl as a white solid.

2. Synthesis of 2,9-dimethoxytriphenylene

In a 2000 mL round-bottom flask equipped with a nitrogen inlet and astir bar, 3,3′-dimethoxy-o-terphenyl (61.3 g, 0.211 mol) was dissolvedin anhydrous methylene chloride (1000 mL). Iron (III) chloride (68.6 g,0.423 mol) was then added, and the mixture was stirred overnight. In themorning an additional two equivalents of iron (III) chloride were added,and the reaction reached completion within one hour. Methanol and waterwere added to the mixture and the organic layer was separated, driedover magnesium sulfate, and evaporated to dryness. The crude product waspurified by silica gel column chromatography with 60/40 methylenechloride/hexane was the eluent to give 50.7 g of a light yellow solidthat was recrystallized from 700 mL of acetonitrile to yield 49.1 g of2,9-dimethoxytriphenylene.

3. Synthesis of 2,9-dihydroxytriphenylene

2,9-dimethoxytriphenylene (49.1 g, 0.170 mol) and pyridine hydrochloride(200 g, 1.70 mol) were placed in a 500 mL round-bottom flask equippedwith a stir bar, reflux condenser, and a nitrogen inlet and heated at220° C. for 90 minutes. The solution was cooled and water was added,resulting in the formation of a white precipitate, which was collectedby vacuum filtration, washed with water, and dried in vacuo to yield43.7 g (96%) of 2,9-dihydroxytriphenylene.

4. Synthesis of triphenylene-2,7-diyl bis(trifluoromethanesulfonate)

To a cooled solution (0° C.) of 2,9-dihydroxytriphenylene (17.5 g, 65mmol) and pyridine (300 mL) in a 1000 mL round bottom flask equippedwith a stir bar and nitrogen inlet was added dropwisetrifluoromethanesulfonyl anhydride (38.7 g, 137 mmol). The reactionmixture was allowed to stir overnight at room temperature. Afterevaporation of the pyridine, the resulting solid was stirred withmethanol (500 mL) and collected by vacuum filtration to afford 32 g of awhite powder that was recrystallized from 500 mL of 30/70heptane/dichloroethane, yielding 28.3 g (82%) of2,9-bis(trifluoromethanesulfonyl)triphenylene.

5. Synthesis of Compound 19S

A mixture of triphenylene-2,7-diyl bis(trifluoromethanesulfonate) (2 g,3.8 mmol), dibenzothiophene-4-boronic acid (3.5 g, 15 mmol), potassiumfluoride (1.5 g, 25 mmol) and THF 100 mL was prepared. Nitrogen wasbubbled directly in the mixture for 1 hour. Next potassium acetate (17mg, 0.08 mmol) and triscyclohexyl phosphine (26 mg, 0.09 mmol) wereadded, and then the nitrogen was bubbled in the mixture for another 30minutes. The mixture was stirred at room temperature for two days. Thenthe reaction was cooled to room temperature. The precipitation wascollected by filtration. Potassium acetate (17 mg, 0.08 mmol) andtriscyclohexyl phosphine (26 mg, 0.09 mmol) were added and then thenitrogen was bubbled in the mixture for another 15 minutes. The mixturewas stirred at room temperature for another two days. The grey solid wasput in one soxlet extractor and washed by refluxing THF overnight. Thesolid in the extractor was collect to provide 2.1 gram white solid(yield 92%).

Example 8 Compound 22S

Step 1

A mixture of 2,6-dichloropyridine (13 g, 88 mmol),dibenzothiophene-4-boronic acid (5 g, 22 mmol), potassium phosphatetribasic (28 g, 132 mmol), toluene 300 mL and water 30 mL was prepared.Nitrogen was bubbled directly in the mixture for 1 hour. Next trisdibenzylideneacetone (0.54 g, 1.3 mmol) was added, and then nitrogen wasbubbled into the mixture for another 20 minutes. The mixture was stirredat room temperature for two days. Then the organic layer was collectedand the aqueous layer was extracted by dichloromethane. The combinedorganic layers were dried over magnesium sulfate and concentrated. Thecrude product was purified by silica gel flash chromatography with up to10% ethyl acetate in hexanes to give 5 grams of yellow solid. It wasfurther recrystallized from dichloroethane/heptane to obtain 2.5 gramsof white sold (39%).

2. Synthesis of Compound 22S

A mixture of4,4,5,5-tetramethyl-2-(triphenylen-2-yl)-1,3,2-dioxaborolane (2.2 g, 6.1mmol), 2-chloro-6-(dibenzothiophen-4-yl)pyridine (1.5 g, 5.1 mmol),potassium phosphate tribasic (3.3 g, 15.3 mmol), toluene 150 mL andwater 15 mL was prepared. Nitrogen was bubbled directly in the mixturefor 40 minutes. Next tris dibenzylideneacetone dipalladium (56 mg, 0.06mmol) and bis(cyclohexyl)-2-biphenylphosphine (100 mg, 0.24 mmol) wereadded, and then nitrogen was bubbled in the mixture for another 17minutes. The reaction mixture was refluxed overnight under nitrogen. Theprecipitation was collected by filtration and washed by toluene,dichloromethane and methanol. Then the product was dissolved in 250 mLboiling xylene, filtered through a small magnesium sulfate plug. Thefiltration was heated to reflux to dissolve all the solid and allowed toslowly cool down. The recrystallized product was obtained as 2.3 gramwhite solid (93%).

Example 9 Compound 21S 1. Synthesis of2-chloro-6-(3-methoxyphenyl)pyridine

A mixture of m-methoxy-phenylboronic acid (10 g, 65.8 mmol),2,6-dichloropyridine (9.7 g, 65.8 mmol), potassium carbonate (27.3 g,197.4 mmol), triphenylphosphine (2.07 g, 7.9 mmol), dimethoxyethane 250mL and water 80 mL was prepared. Nitrogen was bubbled directly in themixture for 20 minutes. Then palladium acetate was added (0.44 g, 2.0mmol). Nitrogen was bubbled again in the mixture for another 10 minutes.The mixture was heated to reflux under nitrogen overnight. The reactionmixture was cooled to room temperature. The organic layer was separatedand the aqueous layer was extracted with dichloromethane. The combinedorganic layers were dried over magnesium sulfate, filtered andevaporated. The mixture was purified by silica column with up to 10%ethyl acetate in hexanes to gain 6.5 g colorless oil (45%).

2. Synthesis of2-(dibenzo[b,d]thiophen-4-yl)-6-(3-methoxyphenyl)pyridine

A mixture of 2-chloro-6-(3-methoxyphenyl)pyridine (3.5 g, 16 mmol),dibenzothiophene-4-boronic acid (4 g, 17.5 mmol), potassium phosphate(10.2 g, 48 mmol), dimethoxyethane 500 mL and water 50 mL was prepared.Nitrogen was bubbled directly in the mixture for 15 minutes. Next trisdibenzylideneacetone dipalladium (147 mg, 0.16 mmol) and2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (263 mg, 0.64 mmol) wereadded, and then nitrogen was bubbled in the mixture for another 15minutes. The reaction mixture was heated to reflux overnight undernitrogen. The next day the reaction mixture was cooled to roomtemperature. The organic layer was separated and the aqueous layer wasextracted with dichloromethane. The combined organic layers were driedover magnesium sulfate, filtered and evaporated. The mixture waspurified by silica column with up to 10% ethyl acetate in hexanes togain 3.8 g yellow solid (65%).

3. Synthesis of 3-(6-(dibenzo[b,d]thiophen-4-yl)pyridin-2-yl)phenol

2-(dibenzo[b,d]thiophen-4-yl)-6-(3-methoxyphenyl)pyridine (3.8 g, 10.3mmol) was dissolved in 120 mL dichloromethane. The solution was cooledto 0° C. under nitrogen. BBr₃ (22.8 mL, 1M in hexane) was slowly addedin at 0° C. and then was slowly brought up to room temperature. Themixture was stirred at room temperature overnight. A brown solid wasobserved to form. The reaction was quenched by adding 100 mL waterslowly. The dichloromethane was removed by rotovap. Then the mixture wasrefluxed for three hours. Saturated sodium bicarbonate solution wasadded to neutralize the mixture, which was extracted by dichloromethaneand ethyl acetate. The combined organic layers were dried over magnesiumsulfate, filtered and concentrated under reduced pressure to obtain 4gram glassy dark brown solid. The product was used for next step withoutfurther purification.

4. Synthesis of 3-(6-(dibenzo[b,d]thiophen-4-yl)pyridin-2-yl)phenyltrifluoromethanesulfonate

3-(6-(dibenzo[b,d]thiophen-4-yl)pyridin-2-yl)phenol (4 g, 11.3 mmol) wassuspended in 100 mL pyridine, cooled to −10° C. with acetone/ice bath.Triflate anhydride (2.29 mL, 13.6 mmol) was slowly added under nitrogen.The mixture was stirred at 0° C. for two hours then poured intosaturated sodium bicarbonate solution 200 mL. The mixture was extractedby ethyl acetate. The combined organic layers were dried over magnesiumsulfate, filtered and evaporated. The mixture was purified by silicacolumn twice with up to 15% ethyl acetate in hexanes. The product wasthen precipitated from its dichloromethane solution by adding hexanes togain 1.8 gram white color solid (the combined yield of last two steps is36%).

5. Synthesis of Compound 21S

A mixture of 3-(6-(dibenzo[b,d]thiophen-4-yl)pyridin-2-yl)phenyltrifluoromethanesulfonate (1.65 g, 3.4 mmol),4,4,5,5-tetramethyl-2-(triphenylen-2-yl)-1,3,2-dioxaborolane (1.32 g,3.7 mmol), potassium phosphate (2.16 g, 10.2 mmol), toluene 100 mL andwater 10 mL was prepared. Nitrogen was bubbled directly in the mixturefor 25 minutes. Next tris dibenzylideneacetone dipalladium (31 mg, 0.034mmol) and 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (55 mg, 0.14mmol) were added, and then nitrogen was bubbled in the mixture foranother 15 minutes. The reaction mixture was heated to reflux for eighthours under nitrogen. The next day the reaction mixture was cooled toroom temperature. The residue was collected by filtration, washed bytoluene, dichloromethane and methanol excessively to get 1.8 gram greysolid, which was sublimed at 260° C. twice before used for devicefabrication.

Example 10 Compound 4S 1. Synthesis of2,11-bis(3-methoxyphenyl)triphenylenes

A mixture of triphenylene-2,11-diylbis(trifluoromethanesulfonate) (2 g,3.8 mmol), 3-methoxyphenylboronic acid (2.3 g, 15 mmol), potassiumphosphate tribasic (4.8 g, 23 mmol), toluene 100 mL and water 10 mL wasprepared. Nitrogen was bubbled directly in the mixture for 30 minutes.Next tris dibenzylideneacetone dipalladium (70 mg, 0.076 mmol) andbis(cyclohexyl)-2-biphenylphosphine (125 mg, 0.30 mmol) were added, andthen nitrogen was bubbled in the mixture for another 15 minutes. Thereaction was refluxed under nitrogen for three hours. After cooled toroom temperature, the organic layer of the reaction mixture wascollected, dried over magnesium sulfate, and concentrated under reducedpressure. The crude product was purified by silica gel flashchromatograph to give 1.6 g white solid (yield 95%).

2. Synthesis of 3,3′-(triphenylene-2,11-diyl)diphenole

A mixture of 2,11-bis(3-methoxyphenyl)triphenylene (1.6 g, 3.7 mmol) andpyridine hydrochloride (4.3 g, 37 mmol) was heated to 220° C. undernitrogen for two and half hours. The reaction was cooled to roomtemperature, and washed with water. The 1.6 g brown residue wascollected by filtration, dried under vacuum and was used without furtherpurification for next step.

3. Synthesis of3,3′-(triphenylene-2,11-diyl)bis(3,1-phenylene)bis(trifluoromethanesulfonate)

The 3,3′-(triphenylene-2,11-diyl)diphenole (1.6 g, 3.9 mmol) wassuspended in a mixture of 50 mL dichloromethane and 5 mL pyridine. Themixture was cooled to 0° C. by ice/water bath. Triflate anhydride (1.44mL, 8.5 mmol) was dissolved in 30 mL dichloromethane and slowly addedinto the reaction mixture under nitrogen at 0° C. Then the reaction wasstirred at room temperature under nitrogen overnight. Methanol 20 mL wasadded to the reaction. The mixture was concentrated by rotovap. Theresidue was suspended in water then was collected by filtration. Afterwashed with water, the residue was dried under vacuum. The crude productwas purified by silica flash chromatograph with up to 30%dichloromethane in hexanes to give white solid 1.6 gram (combined yieldof last two steps: 65%).

4. Synthesis of Compound 4S

The mixture of3,3′-(triphenylene-2,11-diyl)bis(3,1-phenylene)bis(trifluoromethanesulfonate)(1.6 g, 2.4 mmol), dibenzothiophene-4-boronic acid (2.7 g, 12 mmol),potassium phosphate tribasic (3.4 mmol, 16 mmol), toluene 100 mL andwater 50 mL was prepared. Nitrogen was bubbled directly in the mixturefor 1 hour. Next tris dibenzylideneacetone dipalladium (44 mg, 0.048mmol) and bis(cyclohexyl)-2-biphenylphosphine (78 mg, 0.19 mmol) wereadded, and then nitrogen was bubbled in the mixture for another 30minutes. The reaction was refluxed overnight. After the reaction wascooled to room temperature, the residue was collected by filtration andwashed by methanol and dichloromethane to provide final product.

Example 11 Compound 23S 1. Synthesis of 4-phenyldibenzothiophene

10 g (41.6 mmol) 4-dibenzothiophene boronic acid, 6.25 g (39.6 mmol)bromobenzene, 366 mg (0.39 mmol) Pd₂(dba)₃, 656 mg (1.6 mmol) S-phose,25.4 g (120 mmol) K₃PO₄, 180 mL toluene and 20 mL water were charged ina 500 mL flask. The mixture was heated up to reflux under nitrogen forovernight. The reaction mixture was purified by silica gel columnchromatography with pure hexane as elute. ˜8.5 g (83%) white solid wasobtained as product which was confirmed by MS.

2. Synthesis of 4-phenyldibenzothiophene-6-boronic acid

3.5 g (13.4 mmol) 4-phenyldibenzothiophene was dissolved in ˜30 mLanhydrous THF in a three necked 250 mL flask and cooled down to −78° C.To the mixture, 17 mL (27 mmol) 1.6 M BuLi in hexane was added andstirred for 30 minutes. The cooling batch was removed and let reactionkept stirring for overnight. The reaction mixture was cooled down againto −78° C. and 4.5 mL (40 mmol) trimethyl borate was added and stirredat room temperature for 4 hours. ˜100.1 M HCl was added and keptstirring for 1 hour. The mixture was extracted by ethyl acetate and theorganic extracts were combined. The solvent was evaporated to dryness.The solid was added with ˜100 mL 20% ethyl acetate in hexane was stirredfor few hours and then filtered. The filtered solid washed by hexane fewtimes. ˜2.5 g white solid was obtained as product which was confirmed byproton NMR.

3. Synthesis of Compound 23S

2.4 g (7.89 mmol) above boronic acid, 3.3 g (7.2 mmol)3-(triphenylen-2-yl)phenyl trifluoromethanesulfonate, 67 mg (0.08 mmol)Pd₂(dba)₃, 120 mg (0.3 mmol) S-phose, 4.6 g (21.7 mmol) K₃PO₄, 90 mLtoluene and 10 mL water were charged in a 250 mL flask. The mixture washeated up to reflux under nitrogen for 6.5 hours. The reaction mixturewas separated with separation funnel and the organic phase was purifiedby silica gel column chromatography using 20% dichloromethane in hexaneas elute and recrystallization from toluene and hexane mixture. ˜3.8 g(94%) white solid was obtained as product which was confirmed by protonNMR.

Example 12 Compound 24S 1. Synthesis of 2,8-diphenylbenzothiophene

7.0 g (20.4 mmol) 2,8-dibromodibenzothiophene, 6.4 g (51.1 mmol)phenylboronic acid, 187 mg (0.2 mmol) Pd₂(dba)₃, 335 mg (0.8 mmol)S-phose, 13 g (61.2 mmol) K₃PO₄, 90 mL toluene and 10 mL water werecharged in a 250 mL flask. The mixture was heated up to reflux undernitrogen for 4 hours. The reaction mixture was separated with separationfunnel and the organic phase was purified by silica gel columnchromatography using 20% dichloromethane in hexane as elute. ˜6.6 g(96%) white solid was obtained as product which was confirmed by GC-MS.

2. Synthesis of 2,8-diphenyldibenzothiophene-4-boronic acid

3.8 g (11.3 mmol) 2,8-diphenylbenzothiophene was dissolved in ˜30 mLanhydrous THF in a 250 mL three necked flask. To the mixture, ˜18 mL(28.3 mmol) 1.6 M BuLi in hexane was added at −78° C. under nitrogen.The mixture was warned up to room temperature and kept stirring for 18hours. The reaction mixture cooled down to −78° C. again and 3.8 mL (34mmol) trimethyl borate was added and kept mixture stirred for 4 hours atroom temperature then added ˜60 mL 1M HCl with stirring for 1 hour. Themixture was extracted by ethyl acetate and the organic phases werecombined. The solvent was evaporated to dryness. The solid was addedwith ˜100 mL 20% ethyl acetate in hexane. It was stirred for few hoursand then filtered. The filtered solid was washed with hexane 3 times.˜2.2 g white solid was obtained as product which was confirmed by protonNMR.

3. Synthesis of Compound 24S

2.0 g (5.26 mmol) 2,8-diphenyldibenzothiophene-4-boronic acid, 2.18 g(4.78 mmol) 3-(triphenylen-2-yl)phenyl trifluoromethanesulfonate, 45 mg(0.05 mmol) Pd₂(dba)₃, 80 mg (0.19 mmol) S-phose, 3.2 g (14 mmol) K₃PO₄,90 mL toluene and 10 mL water were charged in a 250 mL flask. Themixture was heated up to reflux under nitrogen for overnight. Thereaction mixture was separated with separation funnel and the organicphase was purified by silica gel column chromatography using 20%dichloromethane in hexane as elute and recrystallization from tolueneand hexane mixture. ˜2.52 g (84%) white solid was obtained as productwhich was confirmed by proton NMR.

Example 13 Compound 25S 1. Synthesis of 2,8-diphenylbenzothiophene

7.0 g (20.4 mmol) 2,8-dibromodibenzothiophene, 6.4 g (51.1 mmol)phenylboronic acid, 187 mg (0.2 mmol) Pd₂(dba)₃, 335 mg (0.8 mmol)S-phose, 13 g (61.2 mmol) K₃PO₄, 90 mL toluene and 10 mL water werecharged in a 250 mL flask. The mixture was heated up to reflux undernitrogen for 4 hours. The reaction mixture was separated with separationfunnel and the organic phase was purified by silica gel columnchromatography using 20% dichloromethane in hexane as elute. ˜6.6 g(96%) white solid was obtained as product which was confirmed by GC-MS.

2. Synthesis of 2,8-diphenyldibenzothiophene-4-boronic acid

3.8 g (11.3 mmol) 2,8-diphenylbenzothiophene was dissolved in ˜30 mLanhydrous THF in a 250 mL three necked flask. To the mixture, ˜18 mL(28.3 mmol) 1.6 M BuLi in hexane was added at −78° C. under nitrogen.The mixture was warmed up to room temperature and was kept stirring for18 hours. The reaction mixture was cooled down to −78° C. again and 3.8mL (34 mmol) trimethyl borate was added and the mixture was keptstirring for 4 hours at room temperature. ˜60 mL 1M HCl was then addedwith continuous stirring for 1 hour. The mixture was extracted by ethylacetate and the organic phases were combined. The solvent was evaporatedto dryness. The solid was added with ˜100 mL 20% ethyl acetate in hexanewas stirred for few hours and then filtered. The filtered solid washedwith hexane. ˜2.2 g white solid was obtained as product which wasconfirmed by proton NMR.

3. Synthesis of 2,4,8-triphenylbenzothiophene

5.5 g (14.5 mmol) 2,8-diphenyldibenzothiophene-4-boronic acid, 2.3 g(14.5 mmol) bromobenzene, 135 mg (0.15 mmol) Pd₂(dba)₃, 238 mg (0.58mmol) S-phose, 9.2 g (43.2 mmol) K₃PO₄, 180 mL toluene and 20 mL waterwere charged in a 500 mL flask. The mixture was heated up to refluxunder nitrogen for overnight. The reaction mixture was separated withseparation funnel and the organic phase was purified by silica gelcolumn chromatography using 20% ethyl acetate in hexane as elute. ˜5.1 g2, 4, 8-triphenylbenzothiophene white solid was obtained as productwhich was confirmed by proton NMR.

4. Synthesis of 2,4,8-tiphenyldibenzothiophene-6-boronic acid

5.0 g (12.13 mmol) 2,4,8-triphenylbenzothiophene was dissolved in ˜100mL anhydrous THF in a 250 mL three necked flask. To the mixture, ˜19 mL(30.3 mmol) 1.6 M BuLi in hexane was added at −78° C. under nitrogen.The mixture was warned up to room temperature and kept stirring for 18hours. The reaction mixture was cooled down to −78° C. again and 3.8 mL(34 mmol) trimethyl borate was added and kept mixture stirred for 4hours at room temperature then added ˜100 mL 1M HCl with stirring for1.5 hour. The mixture was extracted by ethyl acetate and the organicphases were combined. The solvent was evaporated to dryness. The solidwas added with ˜150 mL 20% ethyl acetate in hexane. The mixture wasstirred for few hours and then filtered. The filtered solid was washedwith hexane 3 times. ˜4.5 g white solid was obtained as product whichwas confirmed by proton NMR.

5. Synthesis of Compound 25S

3.5 g (7.67 mmol) 2,4,8-tiphenyldibenzothiophene-6-boronic acid, 3.2 g(6.98 mmol) 3-(triphenylen-2-yl)phenyl trifluoromethanesulfonate, 64 mg(0.077 mmol) Pd₂(dba)₃, 115 mg (0.30 mmol) S-phose, 4.5 g (22 mmol)K₃PO₄, 90 mL toluene and 10 mL water were charged in a 250 mL flask. Themixture was heated up to reflux under nitrogen for overnight. Thereaction mixture was separated with separation funnel and the organicphase was purified by silica gel column chromatography using 25%dichloromethane in hexane as elute and recrystallization from tolueneand hexane mixture. ˜4.5 g (92%) white solid was obtained as productwhich was confirmed by proton NMR.

Example 14 Compound 20

3.9 g (18.4 mmol) dibenzofurane-4-boronic acid, 7.0 g (15.4 mmol)3-(triphenylen-2-yl)phenyl trifluoromethanesulfonate, 141 mg (0.154mmol) Pd₂(dba)₃, 252 mg (0.46 mmol) S-phose, 9.8 g (46 mmol) K₃PO₄, 180mL toluene and 20 mL water were charged in a 500 mL flask. The mixturewas heated up to reflux under nitrogen for overnight. The reactionmixture was separated with separation funnel and the organic phase waspurified by silica gel column chromatography using 20% dichloromethanein hexane as elute. ˜6.2 g (87%) white solid was obtained as productwhich was confirmed by proton NMR.

Device Examples

All example devices were fabricated by high vacuum (<10⁻⁷ Torr) thermalevaporation. The anode electrode is ˜800 or 1200 Å of indium tin oxide(ITO). The cathode consisted of 10 Å of LiF followed by 1,000 Å of Al.All devices are encapsulated with a glass lid sealed with an epoxy resinin a nitrogen glove box (<1 ppm of H₂O and O₂) immediately afterfabrication, and a moisture getter was incorporated inside the package.

The organic stack of Device Examples 1-30 in Tables 1 and 2 consisted ofsequentially, from the ITO surface, 100 Å of Compound A as the holeinjection layer (HIL), 300 Å of4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD) as the holetransporting layer (HTL), 300 Å of the invention compound doped with 10or 15 wt % of an Ir phosphorescent compound as the emissive layer (EML),50 or 100 Å of HPT or the invention compound as the ETL2 and 400 or 450Å of Alq₃ (tris-8-hydroxyquinoline aluminum) as the ETL1.

Comparative Examples 1 and 2 were fabricated similarly to the DeviceExamples except that the CBP is used as the host.

The device structures and data are summarized in Tables 1 through 5.Table 1 shows device structure and Table 2 shows corresponding measuredresults for those devices, whereas each of Tables 3 through 5 show boththe device structure and measured experimental results. As used herein,Compound A, Compound B, NPD and HPT, have the following structures:

TABLE 1 Device ITO thickness Example Host Dopant % ETL2 (Å) ETL1 (Å)(nm) Compar- CBP B 10% HPT (50) Alq₃ (450) 120 ative 1 Compar- CBP A 10%HPT (50) Alq₃ (450) 120 ative 2 1 1S A 10% HPT (50) Alq₃ (450) 120 2 1SA 10% 1S (100) Alq₃ (400) 120 3 1S A 15% HPT (50) Alq₃ (450) 120 4 1S A15% 1S (100) Alq₃ (400) 120 5 2S A 10% HPT (50) Alq₃ (450) 120 6 2S A10% 2S (100) Alq₃ (400) 120 7 2S A 15% HPT (50) Alq₃ (450) 120 8 2S A15% 2S (100) Alq₃ (400) 120 9 2S B 10% HPT (50) Alq₃ (450) 120 10 2S B10% 2S (100) Alq₃ (400) 120 11 2S B 15% HPT (50) Alq₃ (450) 120 12 2S B15% 2S (100) Alq₃ (400) 120 13 20S  A 10% 20S (100) Alq₃ (400) 120 1420S  A 10% HPT (50) Alq₃ (450) 120 15 9S A 10% 20S (100) Alq₃ (400) 12016 9S A 10% HPT (50) Alq₃ (450) 120 17 22S  A 10% 22S (100) Alq₃ (400)120 18 22S  A 10% HPT (50) Alq₃ (450) 120 19 21S  A 10% 21S (100) Alq₃(400) 120 20 21S  A 10% HPT (50) Alq₃ (450) 120 21 23S  A 15% 23S (100)Alq₃ (400) 120 22 23S  A 15% HPT (50) Alq₃ (450) 120 23 23S  A 10% 23S(100) Alq₃ (400) 120 24 23S  A 10% HPT (50) Alq₃ (450) 120 25 24S  A 10%24S (100) Alq₃ (400) 120 26 24S  A 10% HPT (50) Alq₃ (450) 120 27 5S A10% 5S (100) Alq₃ (400) 120 28 5S A 10% HPT (50) Alq₃ (450) 120 29 2O A10% 2O (100) Alq₃ (400) 120 30 2O A 10% HPT (50) Alq₃ (450) 120

TABLE 2 At L = 1000 cd/m² At J = 40 mA/cm² Device CIE Emission FWHM V LEEQE PE L₀ LT_(80%) Example X Y max (nm) (nm) (V) (cd/A) (%) (lm/W)(cd/m²) (hr) Comparative 1 0.331 0.627 521 67 6.1 61.0 17 31.4 16,935 87Comparative 2 0.346 0.613 522 75 6.2 57.0 16 28.9 13,304 105 1 0.3470.610 526 76 5.9 60.6 17 32.3 14,083 270 2 0.345 0.612 526 75 6.4 54.915 26.9 14,028 310 3 0.348 0.609 526 76 5.9 60.1 17 32.0 14,092 288 40.346 0.611 526 75 6.4 54.0 14.8 26.5 13,946 306 5 0.347 0.612 526 755.5 67.1 18 38.3 16,615 244 6 0.346 0.612 527 74 6.2 59.6 16 30.2 16,160300 7 0.352 0.608 527 77 5.6 62.5 17 35.0 15,726 224 8 0.350 0.609 52676 6.2 57.1 16 28.9 15,716 260 9 0.341 0.619 525 69 6.2 59.9 16.2 30.314,641 380 10 0.343 0.618 525 72 6.8 50.2 13.6 23.2 14,069 450 11 0.3430.620 527 69 5.9 54.3 14.6 28.9 17,088 194 12 0.341 0.620 527 68 6.540.5 10.9 19.6 13,744 620 13 0.356 0.607 528 76 6.4 60.9 16.8 29.815,974 150 14 0.356 0.607 528 76 5.7 66.6 18.4 38.1 15,414 134 15 0.3660.600 528 75 6.0 52 14.2 25 15,950 60 16 0.357 0.608 528 75 6.0 60 16.431.2 17,100 70 17 0.375 0.587 532 78 8 29.3 8.2 11.5 8,755 91 18 0.3740.590 532 76 7.5 39.2 11 16.4 10,865 82 19 0.367 0.597 532 82 8.5 35.49.8 13.1 10,058 338 20 0.364 0.600 532 82 7.9 44.5 12.3 17.7 11,682 24021 0.365 0.601 528 76 6.9 49.5 13.7 22.5 14,135 620 22 0.363 0.603 52876 6.2 56.5 15.7 28.6 15,067 457 23 0.362 0.602 529 77 7.2 52.4 14.622.9 14,186 378 24 0.364 0.601 529 77 6.6 55.1 15.4 26.2 13,810 343 250.363 0.603 530 78 6.8 52.3 14.5 29.8 14,994 175 26 0.363 0.602 530 786.3 51.9 14.4 36.7 14,061 150 27 0.385 0.588 538 86 7.4 30.7 8.6 13.010,211 1.3 28 0.382 0.590 538 86 6.8 36.4 10.2 16.8 11,305 2.0 29 0.3520.609 528 79 6.6 56.8 15.7 27.0 15,207 305 30 0.355 0.607 528 78 6 63.317.4 33.1 15,219 240

From Device Examples 1-30, it can be seen that Compounds 1S, 2S, 20S,9S, 23S, 24S and 2O as hosts in green phosphorescent OLEDs give highdevice efficiency (LE>40 cd/A at 1000 cd/m²), indicating thetriphenylene and benzothiophene combinations, either directly linked orm-phenylene-linked have triplet energy high enough for efficient greenelectrophosphorescence.

The high stability of devices incorporating Compounds 1S, 2S, 21S, 23Sand 2O as the host is notable. Device Example 1 and Comparative Example2 are only different in the host. Device Example 1 uses Compound 1 asthe host whereas Comparative Example 2 uses the commonly used host CBP.The lifetime, T₈₀% (defined as the time required for the initialluminance, L₀, to decay to 80% of its value, at a constant currentdensity of 40 mA/cm² at room temperature) are 270 hours and 105 hoursrespectively, with Device Example 1 having a slightly higher L₀. Thistranslates to almost a 3 fold improvement in the device stability.Similarly, Device Example 5 using Compound 2S as the host, is at least2.5 times more stable than Comparative Example 2. Device Example 9 usingCompound 2S as the host, is at least 3 times more stable thanComparative Example 1 with CBP as the host. It is also notable that thecompounds may function very well as an enhancement layer material(ETL2). Device Example 10 and Device Example 9 both have Compound 2S asthe host, but Compound 2 and HPT as the enhancement layer respectively.Device Example 10 and Device Example 9 have T_(0.8) of 450 and 380 hoursrespectively, indicating the good performance of Compound 2S as theenhancement layer material. Device Example 21 has T_(0.8) of 620 hourswhich is significantly higher than the lifetime of Comparative Example 1or 2 device with CBP.

The data suggest that triphenylene containing benzothiophenes,particularly triphenylene containing dibenzothiophenes, are excellenthost and enhancement layer materials for phosphorescent OLEDs, providingas least the same efficiency and multiple times of improvement instability compared to the commonly used CBP as the host. More conjugatedversions of triphenylene containing benzothiophenes, for exampletriphenylene and benzothiophene units linked via p-phenylene (such as4,4′-biphenyl) may be very suitable for lower energy (yellow to red)phosphorescent OLEDs.

Table 3 shows device structures and measured experimental results forsome devices having an emissive layer with an interface between a firstorganic layer and a second organic layer, where the host and the dopant,i.e., the non-emissive material is the same material in both layers andthe phosphorescent material is the same material in both layers, but theconcentrations are different. All of the devices in Table 3 had a 100 Åhole injection layer of Compound A, a 100 Å enhancement layer (ETL2) ofdifferent materials depending on the specific device, a 400 Å electrontransport layer (ETL1), and an LiF/Al cathode. The emissive layerincluded a first organic layer and a second organic layer with aninterface between them, where the first organic layer was 300 Å of anon-emissive material (the “host” in Table 3) at a concentration of 70wt % and a phosphorescent material (the “dopant” of Table 3) at aconcentration of 30 wt %, and the second organic layer was 300 Å of thesame non-emissive material (the “host” in Table 3) but at aconcentration of 90 wt % and the same phosphorescent material (the“dopant” of Table 3) but at a concentration of 10 wt %. The specifichost and dopant for each device are identified in Table 3. Thus, thegeneral device structure for the devices of Table 3 was: ITO (1200Å)/Compound A (100 Å)/host (70 wt %):dopant (30 wt %) (300 Å)/host (90wt %):dopant (10 wt %) (300 Å)/ETL2 (100 Å)/Alq₃ (400 Å)/LiF/Al.

TABLE 3 At 1,000 nits At 40 mA/cm² CIE V L.E. E.Q.E. P.E. Lo LT80%Example Host Dopant ETL2 X Y (V) [cd/A] [%] [lm/W] [nits] [h] A Cmpd. ACmpd. 0.36 0.61 6.4 57.5 15.9 28.2 17,225 1060 2S 2S B Cmpd. A HPT 0.360.61 5.8 60.4 16.6 32.7 16,732 1000 2S C Cmpd. B Cmpd. 0.34 0.62 8.446.4 12.5 17.3 15,184 2100 2S 2S D Cmpd. B HPT 0.35 0.62 7.8 54.7 14.822.0 15,04 1350 2S

The devices in Table 3, using Compound 2S as the host and Compound 2S orHPT as the enhancement layer material show high efficiency (>46 cd/A at1000 cd/m²). Even more notable are the stabilities of LT_(80%) of 1000hours (Device Examples A, B and D) or even 2000 hours (Device ExampleC), rendering these devices among the most long-lived greenphosphorescent OLEDs to date.

The good performance and high stability of the devices withtriphenylene-benzothiophene hybrids is believed to be a result of thegood charge balance provided by the triphenylene and benzothiophenecharge transporting units, and the stabilization of the oxidized/reducedstates of the molecule by the i-conjugation provided by thebenzothiophene and triphenylene units.

Table 4 and Table 5 show device structures and measured experimentalresults for devices having an emissive layer containing triphenylene andbenzo-fused thiophene attached to a central pyridine.

All of the devices in Table 4 had a 100 Å hole injection layer ofCompound A, a 300 Å hole transport layer of NPD, a 300 Å emissive layerwith Compound 21S as the host and Compound A as the dopant, a blockinglayer (BL) having materials and thicknesses identified in Table 4, anelectron transport layer (ETL) of Alq having a thickness identified inTable 4, and a LiF/Al cathode. In particular, the BL thickness and theETL thickness have a sum total of 500 Å. The emissive layer was a singlelayer including the host and dopant. The specific percentage of dopantfor each device is identified in Table 4. Thus, the general devicestructure for Table 4 was: ITO (1200 Å)/Compound A (100 Å)/NPD (300Å)/Compound 21S:Compound A x % (300 Å)/BL/Alq (500 Å−BL)/LiF (10)/Al(1000).

TABLE 4 At 1,000 nits At 40 mA/cm² Dopant ETL CIE V L.E. EQE P.E. Lo RTExample Host x % BL (Å) X Y (V) [Cd/A] [%] [lm/W] [nits] 80% E 21S A,10% 21S Alq 0.367 0.597 8.5 35.4 9.8 13.1 10,058 338 100 Å 400 F 21S A,15% 21S Alq 0.370 0.594 8.1 34 9.5 13.2 10,189 335 100 Å 400 G 21S A,10% HPT Alq 0.364 0.600 7.9 44.5 12.3 17.7 11,682 240  50 Å 450 H 21S A,15% HPT Alq 0.369 0.597 7.5 44.3 12.3 18.5 12,377 235  50 Å 450

All of the devices of Table 5 had a 100 Å hole injection layer ofCompound A, a 300 Å hole transport layer having materials identified inTable 5, a 300 Å emissive layer with Compound 22S as the host andCompound A as the dopant, a blocking layer (BL) having materials andthicknesses identified in Table 5, an electron transport layer having athickness that is 500 Å minus the thickness (A) of the blocking layer(BL), and a LiF/Al cathode. In particular, the BL thickness and the ETLthickness have a sum total of 500 Å. The emissive layer was a singlelayer including the host and dopant. The specific percentages for eachdevice is identified in Table 5. Thus, the general device structure forTable 5 was: ITO (1200 Å)/Compound A 100 (Å)/HTL (300 Å)/Compound22S:Compound A x % (300 Å)/BL/Alq (500 Å—BL)/LiF (10)/Al (1000).

TABLE 5 At 1,000 nits At 40 mA/cm2 HTL, Dopant BL ETL CIE V L.E. E.Q.E.P.E. Lo RT 80% Example 300 Å Host x % (Å) (Å) X Y (V) [cd/A] [%] [lm/W][nits] [hr]* I NPD 22S A 10% 22S Alq 0.375 0.587 8 29.3 8.2 11.5 8,75591 300 Å 100 400 J NPD 22S A 10% HPT Alq 0.374 0.590 7.5 39.2 11 16.410,865 82 300 Å  50 450 K NPD 22S A 15% 22S Alq 0.374 0.590 7.9 31.2 8.712.4 9,222 120 300 Å 100 400 L NPD 22S A 15% HPT Alq 0.373 0.594 7.442.4 11.7 18.0 11,522 110 300 Å  50 450 M 22S:Å 22S A 10% 22S Alq 0.3980.579 9.5 16.4 4.7 5.4 5,959 >600 30% 100 400 N 22S:Å 22S A 10% HPT Alq0.393 0.583 9.3 20.2 5.8 6.8 6,863 >600 30%  50 450 *extrapolated data

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore includes variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. Particularly, the triphenylene containing group maybe attached to any position of benzothiophene or benzofuran. It isunderstood that various theories as to why the invention works are notintended to be limiting.

The invention claimed is:
 1. A compound represented by a structureselected from the group consisting of:

wherein X is S or O; wherein R₁ to R₉ are independently selected fromthe group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl,alkynyl, arylalkyl, aryl, and heteroaryl; and wherein each of R₁ to R₉may represent mono substitutions up to the maximum possiblesubstitutions, or no substitutions.
 2. The compound of claim 1, whereinX is O.
 3. The compound of claim 1, wherein X is S.
 4. The compound ofclaim 1, wherein each of R₁ to R₉ is aryl, heteroaryl, or nosubstitution.
 5. The compound of claim 1, wherein at least one R₁, R₂,R₃, or R₄ is other than hydrogen.
 6. The compound of claim 1, wherein atleast one R₅ is other than hydrogen, and wherein the structure isselected from the group consisting of Compound 1G to Compound 30G andCompound 32G to Compound 48G.
 7. The compound of claim 1, wherein atleast one R₆ is other than hydrogen, and wherein the compound has astructure is selected from the group consisting of Compound 2G, Compound3G, Compound 4G, Compound 5G, Compound 9G, Compound 10G, Compound 11G,Compound 16G, Compound 21G, Compound 22G, Compound 23G, Compound 24G,Compound 25G, Compound 26G, Compound 27G, Compound 28G, Compound 35G,Compound 36G, Compound 37G, Compound 38G, Compound 39G, Compound 40G,Compound 43G, Compound 44G, Compound 45G, Compound 46G, Compound 47G,and, Compound 48G.
 8. The compound of claim 1, wherein at least one R₆is other than hydrogen, and wherein the compound has a structure isselected from the group consisting of Compound 2G, Compound 3G, Compound4G, Compound 50, Compound 9G, Compound 10G, Compound 11G, Compound 16G,Compound 21G, Compound 22G, Compound 23G, Compound 24G, Compound 25G,Compound 26G, Compound 27G, Compound 28G, Compound 35G, Compound 36G,Compound 37G, Compound 38G, Compound 39G, Compound 40G, Compound 43G,Compound 44G, Compound 45G, Compound 46G, Compound 47G, and Compound48G.
 9. The compound of claim 1, wherein at least one R₇ is other thanhydrogen, and wherein the compound has a structure is selected from thegroup consisting of Compound 4G, Compound 5G, Compound 9G, Compound 10G,Compound 11G, Compound 16G, 21G, Compound 23G, Compound 25G, Compound26G, Compound 27G, Compound 28G, Compound 37G, Compound 38G, Compound39G, Compound 44G, and Compound 47G.
 10. The compound of claim 1,wherein at least one R₈ is other than hydrogen, and wherein the compoundhas a structure is selected from the group consisting of Compound 4G,Compound 5G, Compound 27G, Compound 28G, Compound 38G, and Compound 39G.11. The compound of claim 1, wherein at least one R₉ is other thanhydrogen, and the compound has a structure of Compound 4G.
 12. Thecompound of claim 1, having a structure selected from the groupconsisting of:

and wherein X is S or O.
 13. The compound of claim 12, wherein X is O.14. The compound of claim 12, wherein X is S.
 15. An organic lightemitting device, comprising: an anode; a cathode; and an organic layerdisposed between the anode and the cathode, wherein the organic layercomprises a compound represented by a structure selected from the groupconsisting of:

 wherein X is S or O; wherein R₁ to R₉ are independently selected fromthe group consisting of hydrogen, alkyl, alkoxy, amino, alkenyl,alkynyl, arylalkyl, aryl, and heteroaryl; and wherein each of R₁ to R₉may represent mono substitutions up to the maximum possiblesubstitutions, or no substitutions.
 16. The organic light emittingdevice of claim 15, wherein the organic layer further comprises aphosphorescent emitter.
 17. The organic light emitting device of claim16, wherein the phosphorescent emitter is an iridium complex.
 18. Theorganic light emitting device of claim 15, wherein the compound is


19. The organic light emitting device of claim 15, wherein the compoundis